1. Field of the Invention
The present invention relates to special effect pigments. More particularly, the present invention relates to mixed metal oxide based special effect pigments, compositions containing mixed metal oxide based special effect pigments and methods of making the same.
2. Description of the Related Art
Special effect pigments are used in a variety of applications including, for example, automotive paints, plastics and other coatings and finishes. Many of the conventional special effect pigments are based on thin, surface treated flakes of base metals (e.g., silver and aluminum) or inorganic materials (e.g., mica with alternating layers of low refractive index materials such as titania and silica or graphite). When incorporated into binder systems or polymers, the flat surfaces of the individual pigment flakes act like microscopic mirrors that reflect incident light (i.e., specular reflection), providing a the surface with a bright metallic-like finish over a wide viewing angle.
Many of the conventional effect pigments, and particularly effect pigments based on mica, tend to be inherently light in color. In cases where a dark colored coating or substrate is desired, the use of such conventional effect pigments can cause the substrate to appear lighter than desired or to have a “washed out” appearance. In addition, most mica based effect pigments tend to provide a relatively consistent metallic appearance over a wide viewing angle. A pigment that looks metallic over a narrower viewing angle is sometimes preferred because it can provide special effects such as a change in apparent color or effect of the substrate depending upon viewing angle and/or illumination angle.